Self-locking electrical plug connector



March 16, 1965 R. E. BARNES SELF-LOCKING ELECTRICAL PLUG CONNECTOR FiledNov. 12 1963 m r 2 I I m a M I I I 0 1 I m E M I n I m u 5.0" Ill 1/ WmC w a P HII'ORNEYS.

United States Patent Ofiice 3,173,74t) SELF-LOCKING ELECTRICAL PLUGCONNECTGR Robert E. Barnes, Trumbull, Comm, assignor to Auto- SwageProducts, Inc, Shelton, COHIL, a corporation of Connecticut Filed Nov.12, 1963, Ser. No. 322,746 8 Claims. (Cl. 339-4217) This inventionrelates generally to self-locking electrical plug connectors, and moreparticularly, to selflocking electrical plug connectors which areadapted for use in the plugboard of a circuit connecting panel of anelectrical calculating or accounting machine or the like.

Prior art connectors of the foregoing type are usually of complexdesign, generally including multiple intricate parts which are dillicultand expensive to manufacture and assemble into the connector, or if madeof a less expensive construction, are unreliable or defective inoperation.

It is an object of the invention to provide an improved, reliable,inexpensive self-locking electrical plug connector of the type which maybe withdrawn from a plugboard by pulling the electrical connector or theelectrical conductor wire to which the connector is attached, but whichmay not normally be pushed from the plugboard by pressure on the nose ofthe connector.

It is a further object of this invention to provide a connector as setforth in the preceding paragraph having an improved spring detentlocking system, particularly one that requires greater force to pull outthe connector than it does to push it into the plugboard.

It is a still further object of the invention to provide a self-lockingelectrical plug connector which is simple and economical in constructionand assembly, not subject to malfunction or accidental disassemblyduring use or handling, rugged and foolproof in Operation, and has along life expectancy.

Other objects and advantages of the present invention will becomeapparent to those skilled in the art upon a consideration of thefollowing detailed description taken in conjunction with the drawings,wherein:

FIG. 1 is a perspective view of a self-locking electrical plug connectorembodying my invention, with a con ductor wire attached;

FIG, 2 is a perspective view of the elements of the spring detentlocking system of the FIG. 1 embodiment;

FIG. 3 is a vertical sectional view taken through the FIG. l'connectorshown in fully mounted position in a plugboard, with some associatedparts;

FIG. 4 is a view similar to H6. 3, but showing the connector partiallywithdrawn from the plugboard, and

FIG. 5 is a sectional view taken substantially on line 55 of FIG. 4.

With reference to the drawings, and particularly FIGS. 1 and 2, myimproved self-locking electrical plug connector is indicated generallyby reference character C, and it comprises three elements: connectorbody 10, cam pin 22, and ball detent spring member 28.

Connector body 19 is elongated, generally cylindrical and hollow, andincludes a tapered annular wall por tion ll, a forward reduced diametersleeve portion 12 having a passage 13, an intermediate raised annularrib 14, and a rear portion 16 adapted to be secured about an end of aconductor wire W which is attached to the connector C. Rear body portion16 may be rigidly secured to the conductor wire W in any convenientmanner, as by crimping, so as to effect both good elec trical andmechanical connection, and if desired piercing members 18, as can beseen in FIG. 3, may be provided on the portion 16 to pierce theconductor wire W to efiect good electrical connection. At one peripheralportion of the body 19 adjacent tapered wall portion 11, a circulardetent opening 20 is formed through the Wall of the body. The connectorbody ill may be formed in any convenient manner; however, in practice ithas been ettectively and economically formed by swaging flat stock intoits completed form illustrated. Whenformed in this manner, an axial slitseam exists which is of no operational significance. Alternatively, theconnector body could be formed of tubular stock to desired shape. In thelatter event, if desired, a slit 17 may be provided to facilitatecrimping of rear portion 15 about the wire W; however, this is anoptional feature and of no operational significance.

Cam pin 22 comprises an elongated rod-like pin portion 24 having at oneof its ends an enlarged cam head 26 in the form of a truncated conicalenlargement with a narrow cylindrical surface 27. Cam pin 22 mayconveniently be formed on a screw machine.

Ball detent spring member 28 comprises an integral elongated rod-likeround wire member which, as may be conveniently done on a wire formingmachine, is bent into a U-shaped spring portion 30, and has an enlargedspherical ball detent portion 32 formed, as by swaging, at one of itsends. The other end 33 of the spring portion 36 is formed to include afiat side 34, the opposite side of which is rounded, as can be seen inFIG. 5, to generally conform to the inner surface of body 16. The balldetent spring member 28 when in its free state has the legs of theU-shaped spring portion 39 diverged substantially more than when theyare in their fully mounted position shown in FIGS. 3 and 4, andtherefore, it must be stressed to be mounted in the connector body N.

T o assemble the spring de-tent system comprising the cam pin 22 andball detent spring member 28 within the connector body 10, withreference to FIG. 3 for purposes of convenience, the cam pin is firstinserted into the connector body, formed as illustrated, axially fromthe right hand side, pin portion 24 first, until it slides into thepassage 13 formed in the reduced portion 12 of the connector body. Thedimensional relationship between the cam pin 22 and the passage 13 issuch as to permit a nice sliding fit of the pin portion 24, butretention of the cam pin within the connector body as a result of camhead 26-tapered wall portion 11 engagement. The ball detent springmember 28 is then inserted into the connector body axially from theright by being preliminarily stressed so as to be able to clear theinternal walls of the connector body, the manipulation being somewhat inthe nature of squeezing the open ends of a hairpin. The open end of themember 28 is inserted first with the ball detent portion 32 oriented tobe aligned with detent opening 20 and the member 28 moved axially intothe body 10 until the ball detent portion is disposed with in the detentopening 20, as shown FIGS. 3 and 4. On reaching this position, the balldetent portion snaps into the detent opening, as a result of the releaseof the stored energy in member 28, and is firmly biased radiallyoutwardly in the opening. With reference to FIG. 3 it will be observedthat at this time the end 33 of member 28 contacts tapered wall portion11, a substantial part of cam head 26 of the cam pin 22 is disposedbetween the ball detent portion 32 and the flat side 34 of the member28, and that the narrow cylindrical surface 27 of the cam head is incontact with the fiat side. The contact of end 33 with tapered wallportion 11 restrains the member 28 axially in the forward direction(toward the left in FIG. 3). However, the end 33 of member 28 is axial-1y unrestrained in the rearward direction (toward the right in FIG. 3),and therefore, the member 28 is float- Patented Mar. 16, 1965 'this isoperationally desirable.

I ingly mounted. This dispositional arrangement effects a certain amountof stability of the parts, as by preventing jamming of the cam pin 22 inpassage 13 in operation, and juxtaposes the cam head 26 relative to theball detent portion 32 and the flat side 34 so as to be poised forsubsequent operation in a desired manner. It should be noted that in theFIG. 3 condition of the connector, the cam head 26 is spaced to theright of the tapered wall portion 11 of the connector body 19, andtherefore, the cam pin 22, under certain operational circumstances, isfree to move axially to the left relative to the body 10.

Assuming the connector C is fully assembled as shown in FIG. 3, if it isdesired to insert it into an aperture of a movable plugboard P, it isinserted therein nose first. During the step of insertion, the balldetent portion 32, which normally extends beyond the periphery of theconnector body 10, will be engaged by the adjacent wall portion of theplugboard surrounding the aperture 0 and be forced to retract radiallyinwardly to permit it to clear through the aperture. This retraction isallowed by combined operation of the cam pin 22 and the ball detentspring member 28. The cam pin 22 is carnmed axially forwardly relativelyto the connector body during this operation to its dotted line positionof FIG. 3 and its solid line position of FIG. 4 as a reaction to theradial retraction of ball detent portion 32 interacting with cam head26. The member 28 is floatingly mounted and slides axially to the rightrelative to the connector body 10 in reaction to force exerted on theball detent portion 32 by the edge of aperture 0 during insertion.During this movement of member 28, an edge of opening in the connectorbody (the right edge with reference to FIG. 3) engages the ball detentportion 32 and exerts a retracting force on it. The combined effect ofthe retracting forces produced by the aperture 0 and opening 20 on balldetent portion 32 is to permit the connector C to be inserted relativelyeasily, which is operationally desirable. After the connector isinserted sufliciently into aperture 0, it will reach the position shownin FIG. 3 wherein the ball detent portion 32 will spring radiallyoutwardly through the detent opening 20 beyond the periphery of theconnector body 10 into a locking position and engage the adjacent edgeof the plugboard aperture 0. In this position, the free end of the pinportion 24 of the cam pin 22 will have engaged the stationary contact C,which may take any convenient known form,.and this will cause the campin 22 to axially retract into the connector body 10 to the solid lineposition of FIG. 3. In this condition, the end 33 contacts tapered wallportion 11 and the connector is mounted and locked in the plugboard P inelectrical engagement with the stationary contact. Any force or pressureexerted on the head of the connector, that is, the portion thereof inthe vicinity of the free end of the pin portion 24 of the cam pin orreduced portion 12 of the connector body, is incapable of pushing theconnector out of the plugboard aperture 0.

The effect of such a force, if exerted, on the cam pin 22 is to cam theball detent portion 32 radially outwardly, asa result of theinterrelation of the conical portion of cam head 26 with the sphericalball detent portion. This urges the ball detent portion radiallyoutwardly into tighter engagement with the adjacent edge of theplugboard aperture 0. Therefore, it is not possible to remove theconnector from the plugboard P by a force exerted on the head of theconnector, short of a destructive blow.

If it is desired to remove the connector C from the plugboard aperture0, a pull on the conducter wire W or the rear portion 16 of theconnector body 10 will effect such removal; however, it requires asubstantial pull to do so. My improved connector is designed to requiregreater force to remove it than is required to insert it, and

With the connector elements disposed as in FIG. 3, a pull toward theright on the wire W will result in the ball detent portion 32 beingforced radially inwardly, ultimately to its position shown in FIG. 4, asa result of its engagement with the adjacent edge of the plugboardaperture 0. However, there is no axial movement of the member 28relative to the connector body because end 33 of the member is incontact with tapered wall portion 11 and prevents the member fromsliding to the left relative to the connector body. Therefore, theconnector body does not exert a retracting force on the ball detentportion 32 when the connector is pulled out of the panelboard. Suchradial retraction of the ball detent portion 32 is permitted when thewire W is pulled because the cam pin 22 is cammed axially toward theleft as viewed in FIG. 3 during such operation to its dotted lineposition. The axial displacement of cam pin 22 to the left relative toconnector body It) creates space for the ball detent portion 32 toretract radially inwardly of the body. FIG. 4 illustrates the conditionof the elements as a connector is being pulled out of the plugboardaperture 0. It requires greater force to pull the connector out of theaperture 0 than is re quired to insert it, because on insertion, due tothe mounting of ball detent spring member 28, there are greaterretractive forces acting on the ball detent portion 32 than onwithdrawal.

It should be observed that my improved connector comprises essentiallythree elements: a connector body 16, a cam pin 22 and a ball detentspring member 28, all of which may be readily and economically formed.These elements lend themselvesto economical mass production and assemblyof the connector is easy and inexpensive. After assembly, my economicalconnector functions better than any known connectors of the typeinvolved which even approach the simplicity of my connector. It isextremely important to note that reliable operation and long life isproduced by my connector largely because of the spherical operatingsurfaces of the ball detent portion of the ball detent spring member.Low cost connectors are known Where detent spring members are formed bystamping them out of sheet stock. These spring members have sharp edgesand burrs on their detent portions, and these dig into the plugboardaround the mounting apertures and stick in and/ or damage the plugboard.My spherical ball detent portion slides smoothly over the plugboard. Iam aware of some connectors that employ ball detents; however, they arevery expensive and require complex intricate elements, such as ballsupports. By combining the spherical ball detent portion and the springportion into single member 28, I have provided an economical andeffective spring detent system.

As will be evident from the foregoing descriptions, certain aspects ofmy invention are not limited to the particular details of constructionof the example illustrated, and I contemplate that various and othermodifications and applications will occur to those skilled in the art.It is, therefore, my intention that the appended claims shall cover suchmodifications and applications as do not depart from the true spirit andscope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A self-locking electrical plug connector for selective insertion intoand removal from an aperture in a plugboard comprising: an elongatedhollow body adapted to be secured at one of its ends to a conductor wireand to be selectively disposed to have its other end extend through theplugboard aperture; means for retaining said body in the plugboardaperture comprising an opening in a side of said body, a retractablymounted detent arranged in said body to extend partially through saidopening to the exterior thereof to a locking position, and biasing meansarranged to bias said detent partially through said opening to itslocking position; said detent and said biasing means being formed by anintegral U-shaped spring member having said detent formed at one of itsends and its other end in contact with an inner surface of said body,said member mounted so as normally to be longitudinally unrestrained inone direction so as to be movable relative to said body toward said oneend of said body on insertion and restrained in the other longitudinaldirection so as not to be movable relative to said body toward saidother end of said body on removal, whereby insertion of the connector ismore readily effected than its removal; said detent being retractable inresponse to insertion of said connector into or pulling of saidconnector out of the plugboard aperture; and means for preventingremoval of said connector out of the plugboard aperture by a forceapplied to said other end of said body comprising a cam pin movablymounted in said body and having a pin portion extending through andprojecting beyond said other end and an enlarged cam head portiondisposed within said body adjacent said detent and arranged to engageand force said detent in a direction out through said opening to thelocking position in response to a force applied to said pin portion,said detent being spherical over all operating surfaces thereof whichengage the rim of said opening or the edges of the plugboard aperture atany time in operation.

2. A connector as defined in claim 1 wherein a substantial part of saidcam head portion is disposed between the ends of said spring member.

3. A connector as defined in claim 2 wherein the end of said springmember that contacts said body has a side in contact with said cam headportion which functions to position and guide said cam pin.

4. A connector as defined in claim 1 wherein said member is formed ofbent Wire and said detent is an enlargement formed at one end of thewire.

5. A connector as defined in claim 1 wherein said other end of said bodyis of reduced size relative to the remainder of said body and includes apassage; said cam pin portion is slidably mounted in said passage; andsaid cam head portion is larger than said passage.

6. A self-locking electrical plug connector for selective insertion intoand removal from an aperture in a plugboard comprising: an elongatedhollow cylindrical body adapted to have one of its axial ends secured toa condoctor Wire; the other axial end of said body being reduced,cylindrical, and having a passage connecting the exterior with theinterior of said body; a cam pin comprising a cam head disposed withinthe interior of said body and a pin portion extending through saidpassage to project to the exterior of said body; an integral detentspring wire member comprising a bent generally U-shaped spring wireportion having a spherical enlargement detent portion formed at one end;a radial opening formed in a side of said body; said member disposedWithin said body with said detent portion normally disposed within andpartially extending through said opening to the exterior of said body toa locking position, and the other spring portion end disposed within andarranged to contact said body and place said spring portion undercompression to bias said detent radially outwardly; said other springportion end being axially unrestrained in one direction so as normallyto be axially movable relative to said body toward said one end of saidbody on insertion and restrained in the other axial direction so as notto be axially movable relative to said body toward said other end ofsaid body on removal; and said cam head disposed contiguous with ravensaid detent portion, whereby said detent portion may retract radiallyinwardly only if said cam pin is free to slide axially out said reducedend and insertion of the connector is more readily effected than itsremoval.

7. A connector as defined in claim 6 wherein a substantial part of saidcam head is disposed between the ends of said spring portion; and saidother spring portion end has a fiat side in contact with said cam headto position and guide it.

8. A self-locking electrical plug connector for selective insertion intoand removal from an aperture in a plugboard comprising: an elongatedhollow body adapted to be secured at one of its ends to a conductor wireand to be selectively disposed to have its other end extend through theplugboard aperture; means for retaining said body in the plugboardaperture comprising an opening in a side of said body, a retractablymounted detent arranged in said body to extend partially through saidopening to the exterior thereof to a locking position, and biasing meansarranged to bias said detent partially through said opening to itslocking position; said detent being retractable in response to insertionof said connector into or pulling of said connector out of the plugboardaperture; means for preventing removal of said connector out of theplugboard aperture by a force applied to said other end of said bodycomprising a cam pin movably mounted in said body and having a pinportion extending through and projecting beyond said other end and anenlarged cam head portion disposed within said body adjacent said detentand arranged to engage and force said detent in a direction out throughsaid opening to the locking position in response to a force applied tosaid pin portion; said detent being spherical over all operatingsurfaces thereof which engage the rim of said opening or the edges ofthe plugboard aperture at any time in operation; and means permittingsaid detent to move in said opening relatively toward said one end ofsaid body on insertion and preventing said detent from moving in saidopening relatively toward said other end of said body on removal,whereby insertion of the connector is more readily effective than itsremoval.

References tilted by the Examiner UNITED STATES PATENTS 1,010,432 12/11Jones 292l7 1,025,157 5/12 Prahar 292-17 2,256,243 9/41 Edwards -52,331,851 10/43 Spooncr 855 2,779,929 1/57 Sesny et a1 339217 2,787,7714/57 Francis 339-217 X 2,903,670 9/59 Sitz 339217 X 2,983,978 5/61Wilgus 85-5 X 3,088,118 10/61 Mavity 339-217 3,085,222 4/63 Watts339-217 3,134,633 5/64 Hatfield 339-217 OTHER REFERENCES Twin DetentPatchcords by AMP, Arnp Incorporated, Harrisburg, Pa, copyright 1962.

JOSE-PH D. SEERS, Primary Examiner. ALBERT H. KAMPE, Examiner.

6. A SELF-LOCKING ELECTRICAL PLUG CONNECTOR FOR SELECTIVE INSERTION INTOAND REMOVAL FROM AN APERTURE IN A PLUGBOARD COMPRISING: AN ELONGATEDHOLLOW CYLINDRICAL BODY ADAPTED TO HAVE ONE OF ITS AXIAL ENDS SECURED TOA CONDUCTOR WIRE; THE OTHER AXIAL END OF SAID BODY BEING REDUCED,CYLINDRICAL, AND HAVING A PASSAGE CONNECTING THE EXTERIOR WITH THEINTERIOR OF SAID BODY; A CAM PIN COMPRISING A CAM HEAD DISPOSED WITHINTHE INTERIOR OF SAID BODY AND A PIN PORTION EXTENDING THROUGH SAIDPASSAGE TO PROJECT TO THE EXTERIOR OF SAID BODY; AN INTEGRAL DETENTSPRING WIRE MEMBER COMPRISING A BENT GENERALLY U-SHAPED SPRING WIREPORTION HAVING A SPHERICAL ENLARGEMENT DETENT PORTION FORMED AT ONE END;A RADIAL OPENING FORMED IN A SIDE OF SAID BODY; SAID MEMBER DISPOSEDWITHIN SAID BODY WITH SAID DETENT PORTION NORMALLY DISPOSED WITHIN ANDPARTIALLY EXTENDING THROUGH SAID OPENING TO THE EXTERIOR OF SAID BODY TOA LOCKING POSITION, AND THE OTHER SPRING PORTION END DISPOSED WITHIN ANDARRANGED TO CONTACT SAID BODY AND PLACE SAID SPRING PORTION UNDERCOMPRESSION TO BIAS SAID DETENT RADIALLY OUTWARDLY; SAID OTHER SPRINGPORTION END BEING AXIALLY UNRESTRAINED IN ONE DIRECTION SO AS NORMALLYTO BE AXIALLY MOVABLE RELATIVE TO SAID BODY TOWARD SAID ONE END OF SAIDBODY ON INSERTION AND RESTRAINED IN THE OTHER AXIAL DIRECTION SO AS NOTTO BE AXIALLY MOVABLE RELATIVE TO SAID BODY TOWARD SAID OTHER END OFSAID BODY ON REMOVAL; AND SAID CAM HEAD DISPOSED CONTIGUOUS WITH SAIDDETENT PORTION, WHEREBY SAID DETENT PORTION MAY RETRACT RADIALLYINWARDLY ONLY IF SAID CAM PIN IS FREE TO SLIDE AXIALLY OUT SAID REDUCEDEND AND INSERTION OF THE CONNECTOR IS MORE READILY EFFECTED THAN ITSREMOVAL.